1. Field of the Invention
The present invention relates to an improvement in an apparatus capable of forming plural images on transfer materials from a single latent image formed on a latent image bearing member.
2. Description of the Prior Art
For the purpose of producing plural images from a single latent image formed on a latent image bearing member, there is already known a process of forming a primary latent image on a screen-shaped photosensitive member (hereinafter called screen) and repeating a step of forming a secondary latent image on a transfer material by modulating ion flow by means of the electric field generated in the apertures of said screen by said primary latent image or repeating a step of forming such secondary latent image on an insulating drum. Said secondary latent image formed on the transfer material is developed and fixed thereon while a secondary latent image formed on said insulating drum is developed, then transferred onto a transfer material and fixed thereon. The apparatus utilizing such screen is capable of ion modulations of several tens to several hundred times with a primary latent image on the screen if it is not easily deteriorated by such modulating step.
In addition to the foregoing there are also known a process of forming a latent image on a conventional layer-structured photosensitive member and repeating the steps of image development and image transfer so as not to attenuate said latent image, and a process of forming a magnetic latent image, instead of the electrostatic latent image, on a magnetic recording member and repeating the steps of image development and image transfer in a similar manner.
In the following description of the present invention, reference will be made to an image forming apparatus utilizing a screen as explained in the foregoing.
The screen to be employed in the present invention is composed of a layered structure of electroconductive members and photoconductive or insulating members having a plurality of minute apertures, is adapted to form a primary latent image corresponding to the image of an original through the steps of electrostatic charging and exposure to light image of said original, and is utilized for forming a secondary latent image on a copy material capable of bearing electrostatic charge thereon by ion modulation in which the passage of ion flow through said apertures is controlled according to the electric field pattern formed in said apertures by said primary latent image. Such electrophotographic process is already disclosed for example in the U.S. Pat. No. 3,582,206 corresponding to the Japanese Patent Publication No. Sho48-5063.
The electrophotographic process utilizing such screen allows, depending upon the layered structure of the screen, secondary latent images to be obtained on copying materials consecutively by plural ion modulation steps on a single primary latent image. Consequently a copying apparatus utilizing such screen is capable of consecutive image formations on plural copy sheets once a latent image is formed on said screen.
The conventional copiers generally interrupt the copying operation in case of a machine trouble such as paper jamming in the course of copying process and form the latent image anew on the photosensitive member after such trouble is resolved. Also the copiers utilizing the above-mentioned screen for consecutive copying from a single latent image effect the formation of the primary latent image anew after the copying operation is interrupted by a machine trouble such as paper jamming. Such reformation of the primary latent image is quite inefficient despite the fact that such apparatus has an ability of forming the copy images consecutively from a single latent image. Such drawback is not limited to the process utilizing the above-mentioned screen but also exists in other processes as explained in the foregoing.